A.) Scope--Definitions
This invention is limited to a heat pump performing an absorption heat cycle using a liquid working medium. For definitional purposes, the working medium comprises at least two substances. One of the substances must have and is defined herein to have a lower boiling temperature and thus a higher vapor pressure in the gaseous phase than the other liquid substance. ("Vapor pressure " or "saturated vapor pressure" is conventionally defined t mean that particular pressure corresponding to a particular temperature at which the substance as a gas is in equilibrium with the substance as a liquid. "Vapor" is conventionally defined as a gas which is at a temperature below its critical temperature and therefore can be liquefied by a suitable increase in pressure.) Typically, the working medium in an absorption refrigeration-heating cycle is most commonly ammonia and water. The ammonia has a lower boiling point and a higher vapor pressure than does water. Another example of a working medium is a solution of water and lithium bromide. Water has a lower boiling temperature and a higher vapor pressure in the gaseous phase for a specified temperature than does the rich solution of lithium bromide. Water in the water-lithium bromide solution functions as the equivalent of ammonia in the ammonia-water working medium. It is contemplated that all such liquid working mediums capable of use or heretofore used in an absorption heat cycle can be utilized in the heat pump of the present invention. In contrast, while some features of the invention may be conceptually applicable to gas-solid adsorbent systems, it is not contemplated that the invention, as defined and disclosed herein, is applicable to solid adsorbent systems for reasons which will be hereafter clarified
To avoid any confusion in terminology, an absorption heat cycle is defined herein to mean one in which the following four steps or phases are sequentially performed:
a.) Boiling or generating a liquid solution in which vapor of the lower boiling point working medium is produced. This cycle step requires heat input and may be defined as endothermic. PA1 b.) Condensing into liquid from its vapor the lower boiling point liquid substance. This cycle step liberates heat and may be viewed as exothermic. PA1 c.) Evaporating the condensed liquid of the lower boiling point liquid substance in step (b) above. This step draws in heat and may be viewed as endothermic. PA1 d.) Absorbing the vapor of the lower boiling point liquid substance into the higher boiling point liquid substance. This step gives off heat and may be viewed as exothermic.
The invention utilizes latent heat resulting from change of state between liquid and gas to effect refrigeration or heating in combination with gas absorption (solute, solvent) all of which are conventional concepts. Absorption is utilized so that the vapor pressure of the solution can be kept lower than the vapor pressure of the refrigerant to permit the process steps to occur as in any conventional absorption process.